prevent memory leakage

previously didn't detect and report the "Conditional jump or move depends on
uninitialised value(s)" error.

When I fixed this, I caught a few curl bugs with it. And then I had to spend
time to make the test suite IGNORE these errors when OpenSSL is used since it
produce massive amounts of valgrind warnings (but only of the "Conditional..."
kind it seems).

So, if a test that requires SSL is run, it ignores the "Conditional..."
errors, and you'll get a "valgrind PARTIAL" output instead of "valgrind OK".

properly, to avoid reading uninited variables when using file:// (valgrind)

uninitialized variables. Pointed out to us by the friendly Valgrind.

gets closed just after the request has been sent failed and did not re-issue
a request on a fresh reconnect like the easy interface did. Now it does!
(define CURL_MULTIEASY, run test case 160)

that uses the multi interface to run the request. It is a great testbed for
the multi interface and I believe we shall do it this way for real in the
future when we have a successor to curl_multi_fdset().

libcurl leaked the last Location: URL.

timed out" even though the reason was different. Fixed this problem by not
setting this timeout to zero when using multi.

curl_easy_perform() invokes. It was previously unlocked at disconnect, which
could mean that it remained locked between multiple transfers. The DNS cache
may not live as long as the connection cache does, as they are separate.

To deal with the lack of DNS (host address) data availability in re-used
connections, libcurl now keeps a copy of the IP adress as a string, to be able
to show it even on subsequent requests on the same connection.

when built ipv6-enabled. I've now made a fix for it. Writing test cases for
custom port strings turned too tricky so unfortunately there's none.

to allow the contents of the env var decide the file name.

a free-without-alloc as the first call

variable to allow the test suite to better control where it ends up.

curl's -P option easier.

present in RFC959... so now (lib)curl supports it as well. --ftp-account and
CURLOPT_FTP_ACCOUNT set the account string. (The server may ask for an account
string after PASS have been sent away. The client responds with "ACCT [account
string]".) Added test case 228 and 229 to verify the functionality. Updated
the test FTP server to support ACCT somewhat.

use to detect libcurl and setup variables for the protocols the installed
libcurl supports: docs/libcurl/libcurl.m4